This section discusses aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light. The statements of this section are not to be understood as admissions about what is in the prior art or what is not in the prior art.
The demand for wideband high data rate communications with spectral efficiencies greater than 1 bit/Second/Hertz has outstripped the capabilities of analog receivers and DSP processors.
For example, GSM cellular telephony devices represent the maximum signal density and speed available in off the shelf conversion and DSP chips. Analog to digital converters and Digital to analog converters for mixed mode signal processing are limited to sample rates of about 2 GSPS. Few DSP FPGA's operate at these rates with manageable power dissipation.
A method and apparatus for testing fiber optic hubs is directed to a fiber optic hub for local area networks and other data communication systems including an internal self-diagnostic and cable test capability for permitting off-line testing of the hub and of fiber optic cables connected to the hub. The hub includes a plurality of optical interfaces each having an optical receiver section and an optical transmitter section and hub-processing circuitry connected to the optical interfaces for processing data signals received by the optical receiver sections and for providing the processed data signals to the transmitter sections to be transmitted back through the network. Hub further includes a test signal source for generating a test signal to be transmitted from the transmitter sections of one or all of the optical interfaces, and a test signal detector connected to the receiver sections of the interfaces for detecting a test signal received by any of the receiver sections and for generating an error indicator signal when the received test signal differs from the transmitted test signal. The transmitter and receiver sections of any hub optical interface can be conveniently tested by looping a fiber optic cable from a transmitter section of any optical interface to the receiver section of any other optical interface and monitoring an error indicator (LED) illuminated by the error indicator signal. The hub also provides a convenient means for testing fiber optic cable connected to the hub.
A method and apparatus for calibrating a lightwave component measurement system is directed to a method and apparatus for calibrating absolute and relative measurements of modulation and/or demodulation transfer characteristics of electro-optical and opto-electrical devices during setup of a lightwave component measurement system for characterizing performance of fiber optic systems and associated components. The lightwave component measurement system calibrated in accordance with the method provides the capability to measure the optical, electrical, and, especially, the electro-optical (E/O) and opto-electrical (O/E) components with specified measurement performance. In accordance with the calibration method, when the lightwave component measurement system is used to characterize an E/O or O/E device, an initial calibration reference is established based on the known characteristics of a lightwave source and lightwave receiver included in the lightwave component measurement system. A measurement is then performed on the calibration reference (the lightwave source or the lightwave receiver), and error correction data are produced and stored in a lightwave component analyzer included in the lightwave component measurement system. The modulation (or demodulation) transfer characteristics are preferably given in terms of the responsivity magnitude and phase versus modulation frequency. A device under test (DUT) then is measured when it replaces its calibrated counterpart in the measurement setup. The lightwave component analyzer uses the error correction data when the E/O or O/E characteristics of the DUT are measured.
A Fiber Optic Link Noise Measurement and Optimization System is directed to an apparatus for optimizing system performance for use in a transmission and signal distribution system which includes at least one fiber optic link having transmission and receiving means. The apparatus includes apparatus for measuring noise signals in each fiber optic link and apparatus for generating system performance data corresponding to the noise signals measured by the noise measurement apparatus.
A method and apparatus for checking continuity of optic transmission is directed to an apparatus for checking continuity of fiber optic links from source to receiver before enabling the source delivers full power so as to thereby prevent eye damage to personnel and provide a supervisory signal to the system user that the link elements are intact and functioning. The apparatus includes a transmitter, a receiver and a detector for detecting that an optical transmission between the transmitter and receiver can be effected.
A Lightwave Component Analyzer relates to a lightwave component analyzer comprising at least an internal optical receiver and preferably also comprising an internal optical source which are selectively connectable by switches configurable by means of an internal or an external instrument controller for calibration and performance of electro-optical, opto-electrical, and optical measurements. The switches are arranged in a switch matrix. The configurable switch matrix is connected by the instrument controller in response to selection of a measurement by a user to facilitate calibration of, and test measurements of devices under test with, the lightwave component analyzer.
A calibration and error correction for electrical-source-to-E/O-device impedance mismatch and O/E-device-to-electrical-receiver impedance mismatch in a lightwave component analyzer is directed to a lightwave component analyzer including at least an internal optical receiver and preferably also including an internal optical source which are selectively connectable by switches configurable by means of an instrument controller for calibration and performance of electro-optical, opto-electrical, and optical measurements. Transmission measurements of E/O devices are corrected for source match errors, and transmission measurements of O/E devices are corrected for load match errors, in addition to frequency response and cross-talk error correction, Response and match error correction provides for improved measurements of test devices with an electrical port having an impedance different from that of the measurement system impedance.
A method and circuit arrangement for monitoring the operating condition of an electro-optical transmission system” is directed to recognizing the status of a “no light” condition at the signal input of a receiving terminal, measured values that correspond to the electrical signal level of received signals are stored at given time intervals. In the absence of digital signals, the contents of the memory, potentially in combination with a further measured value, are searched for a change in the amplitude of the received signal. Given a large level change, a “no light” condition is reported.
A method for measuring pulse distortion is directed to a method for measuring pulse distortion in a digital logic design. A digital logic block of interest is divided into its component primary logic functions. The pulse width distortion characteristics are determined for each primary logic function. The pulse width distortion characteristics are used to develop values representing the minimum pulse width required to guarantee full pulse amplitude propagation through each primary logic function. Thus, pulse distortion is characterized in terms of both width and amplitude components. Pulse width distortion for the entire logic block is then determined by following each logic path through the logic block and statistically summing the pulse width distortion characteristics for each occurrence of each primary logic function in the logic path. Pulse amplitude integrity is checked at the input to each primary logic function by referencing the pre-calculated values for minimum pulse width required to guarantee full pulse amplitude propagation through the primary logic function.
An Electro-optic Automated Test Equipment is directed to Primary and secondary mirrors that constitute a collimator which permit measurements to be made within a reasonably sized equipment enclosure. An incoming laser beam, from a unit undergoing test, has its light dispersed by an integrating sphere from which radiometric measurements may be made. Further, the output from the sphere passes through an avalanche photo diode for detecting laser beam pulse envelopes. These envelopes may be measured for such parameters as pulse width, and interval. A focal plane array camera is provided to measure boresight deviation from the unit undergoing test.
Additionally, traditional phased arrays utilize analog up converters followed by phase shifters and SSPA's and LNA's to drive each element in the phased array. Architecture is inherently band limited due to VSWR effects and group delay as percent bandwidth increases. Analog to digital converters and Digital to analog converters for mixed mode signal processing are limited to sample rates 2 GSPS forcing frequency conversion and band folding to implement bandwidths an octave. Few DSP FPGA's operate at these rates with manageable power dissipation.
An example of a light weight portable phased array antenna is for receiving communication signals from satellites having plurality of subplates, a plurality of antenna nodes supported on the top surface of each subplate, and an electronic control unit to which the subplates are fixed and aligned and a collapsible support stand fixed to the bottom of the electronic control unit opposite the subplates in which the subplates, electronic control unit and stand interconnect to form an easily assembled lightweight antenna assembly that may be disassembled into easily portable components.
Another example of a compact phased array antenna system includes circuitry and an antenna unit. The antenna unit includes a multilayer circuit board. The circuitry provides radio frequency signals, control signals and power to the circuit board. The circuit board has an array of antenna elements on one side thereof, and has a plurality of modules soldered to and projecting outwardly from the opposite side thereof. The modules each have electronic circuitry thereon, which is electrically coupled to the circuit board. Each module includes a thermal transfer element, the heat generated by the electronic components on that module being thermally transferred by the thermal transfer element to a cooling section.
Another example is directed to a method and structure for phased array antenna interconnect using an array of substrate slats. The phased array antenna is formed from an array of apertures having walls containing phase shifter devices for phase shifting and beam steering a radiated beam of the phased array antenna. The phase shifter devices are interconnected with an interconnect structure formed from substrate slats that form the walls of the apertures. The substrate slats may be thin film circuitized column slats having a metal substrate, dielectric layers, metal bias/control circuitry, a shielding layer, and circuit terminations to connect to a phase shifter device attached to the substrate slat.